We had a 2013 - never regretted the sway bar. The awning was definitely worth it especially on sunny days or cooler damp evenings.
We had the high lift axle but not really worth it unless you camp at places other than regular campsites - at the time I believe you got better load rated tires.

We have a 2014 Spirit deluxe, we have all the options you mentioned. We are happy with all three. The awning is something you have to be careful of because it doesn't take much wind to damage it ( rip it off the trailer) we retract it if we are going to be away for any length of time. Some people skip the awning and opt for a free-standing shelter such as the "Clam". I'm very pleased with the anti-sway bar and 18 wheelers pass with no effect on the trailer. The high-lift axle just increases your options as to where you're able to camp. I'd say go for it, much better to have it and not need it, than to need it and not have it. Peace

We are new owners of a barely used 17 SD. It's fully loaded except for the electric jack. Those are three options I would have paid for if we were to order new (which we were about to do.) The awning is really slick and easy to use, the extra clearance is practical and makes it easier for me to back the trailer into my back yard. The anti-sway is an extra measure of safety. But it all depends on your needs.

We have all of the options you are thinking of getting and find them all useful. Also they are all desirable for resale, I know many people won't buy a used Casita if it doesn't have the high lift axle.

We opted for the Clam Pavilion screen house instead of an awning. Sets up at least as quick. Keeps bugs out, With flaps down, keeps weather out. It is our biggest "living room" and "dining room". It is 6'4" in its storage bag, but we have a long bed pickup where storage is no problem. As an extra benefit, the Clam shelter cost about half of the awning.

Love the awning. Great indoor to outdoor transition area. Rain flap. Sun guard. Extended living space. And don't have to store, pack and set up some thing else (separate shelter). I would not tow a trailer without a sway bar. Very inexpensive safety feature.

The sway bar costs $79 if purchased from Casita; $49 if purchased from Amazon but then you will have install the ball on the trailer hitch. We also bought the high lift and awning. Pleased with everything but have yet to do our first camp! ;]

We love our high lift axle. It has enabled us to go places that would have bottomed out the trailer and possibly damaged the holding tanks. You never know where you will end up or where the road will lead. The awning has been great as you can sit outside even in a light rain.